Ingredients

3 large onions, roughly chopped (about 1 1/2 quarts)
3 large carrots, peeled and roughly chopped (about 1 quart)
4 stalks celery, roughly chopped (about 1 quart
12 thyme sprigs
1 whole turkey (12 to 14 pounds total), butterflied according to these instructions, backbone, neck, and giblets reserved
2 tablespoons vegetable oil
Kosher salt and freshly ground black pepper
1 1/2 quartslow sodium homemade or storebought chicken or turkey broth
2 bay leaves
3 tablespoons butter
4 tablespoons flour